Author Note: Part 1 is the background and build up of the story.
Mark had always felt like a lucky guy. He was relatively good-looking, at 5'9" with shaggy brown hair and a moderately athletic build. He was attractive and interesting enough to have a few girlfriends through high school and college. Athletic enough to keep in good hiking-on-the-weekends shape. But, for some reason, he'd landed an absolute bombshell out of college, Tiffany.
Tiffany (all of her friends called her "Tiff") and Mark had met at a bar, after Tiffany had been successfully rejecting college bro after college bro, though Mark caught her smiling after each one. He made some off-hand comment he couldn't remember, and she laughed. They chatted, she saw him the next morning getting coffee, and they realized they lived in the same building. A few weeks talking, and they were dating. Six months later, and Mark was a pretty happy dude.
How, Mark couldn't understand. She was 23 and a year out of college; he was 26 and working a job at a car dealership. She made most of her money as a waitress, but was also doing quite well posting thirst traps on Tiktok. And Mark could see why. She was blonde (not naturally), tan, 5'4", and gorgeous; relatively small waist, with a flat influencer-girl stomach, but DD tits and a nice ass that stayed impossibly round in a thong. Maybe part of her attraction to him, Mark thought, was due to the fact that she definitely fit the "dumb blonde stereotype." Not an idiot, but she was spacey and clueless at times. And had a robust sex drive--Mark thought her pussy walls were probably all cum at this point, although she wasn't big on cumshots or swallowing, and Mark had never broached the idea of anal.
Tiffany liked to show off. Maybe it was the influencer side, but Tiffany absolutely loved being the center of attention. The last steakhouse they went to, the waiter had to ask Tiffany to cover up; her red dress was painted on, and apparently not well enough, as while she leaned over to eat her mashed potatoes she apparently flashed every businessman at the bar. When they went out for drinks, she wore a skirt that could only be described as "a belt", and Mark caught more than one guy staring at her bare ass. Tiffany didn't like wearing much underwear, and was usually in a thong or g-string. At the beach, she found every reason possible to tan topless. Especially when the bros were out playing beach volleyball nearby.
Mark was a lucky guy.
All of this attention made him feel a bit strange; he felt constantly nervous that Tiffany would cheat. She could get any guy she wanted. He knew she wouldn't; and yet, the thought kept bugging him. It was even more confusing that he got a hard-on every time he thought about it. A few times, he had weird dreams where Tiffany would come back home after a night out alone, and she'd smell...different.
Lucky for him, he thought, he saw an ad for a sex therapist doing free first consults. Maybe a therapist, someone who dealt with sex all day, would be able to help him work through this. Why did the thought of his girlfriend going out alone? He went ahead and decided to give the therapist, Jessica, a call.
The call that changed his life.
------------------------------------------
He probably should have been suspicious of Jessica's qualifications on the first Zoom. She was 24 and very cute. And wearing a way-too-tight white tee-shirt with no bra. And with clear nipple piercings. She looked like she was trying out for a sex worker ad, but sure enough, she started talking with him about his sex life. After a few intro questions, and a bit of what Mark swore was flirting, she broached the subject of Mark's concern.
"What do you think about Tiffany? Do you trust her?"
Mark paused. "Yes, I think so. I mean, I don't have a reason not to. She's never done anything. But, I don't know, I feel like she would. Maybe? I don't know. She's kind of stupid. And really hot."
Jessica laughed. "Slow down! Don't worry. This is a common concern. What do you want to learn about her?"
"I don't know. I want to know what she'll do. I almost don't care, I just want her to be mine! Although," he took a breath, "I do get, you know, excited when thinking about it. Which is crazy!"
Jessica paused. "Well, Mark, what do you think about when you think of her cheating?" Jessica's hand seemed to slide from the mouse on video downward, and her arm moved towards the middle of the screen, but Mark didn't notice.
"I mean, it does turn me on. Oh no, does that make me weird?"
"Tell me what thinking of her cheating does, specifically. What do you do? Do you touch yourself?"
Jessica's arm moved a bit, pressed against the side of her bra-less breast and squeezing it towards the other. Her nipple became even more pronounced, and Mark caught a little bit of a catch in her voice at the end. Strange, he thought.
"Yeah, I mean, I'll be honest, I've thought about her cheating. And I've jacked off to it. But I don't think I'd ever want it!"
Jessica's tits heaved for a second after Mark said "jacked off", straining against the shirt. Mark saw a little sweat build up on her forehead, and heard a faint buzzing over the speakers. "Man, she must be taking this seriously if she's sweating" Mark thought.
"Mark, tell me about touching yourself. How big is it? And do you stroke it hard or slow? How tight do you grip it?...for therapy, of course!" Jessica said, her voice raising in pitch a bit.
"Well, I mean, probably 6" and pretty thick I guess. I grab it pretty tight, put some lube on there, and stroke it slowly until I'm ready to bust. Then I bust in a napkin and call it good." Strange therapy session.
Jessica visibly convulsed, leaning forward, her tits swaying. "Oh God, that's helpful Mark" she managed to say after a few seconds. She looked directly at the camera and smiled. "I have an idea for you."
"Why don't you let her...try and cheat? And watch to see what happens. Set her up with a friend you both know, but not too close. And make sure he's attractive. Better yet, find a house party that a bunch of your attractive friends are at and send her there. Tell your friend what's up, and ask him to hit on her. Ask him to keep you informed of what's going on, so you don't feel disconnected. And see what happens!"
Mark thought. "I mean, sure, I guess I could try that. It's making me hard thinking about it, so it can't be bad, right?"
Jessica smiled slyly. "Sure, Mark, I'm sure it's going to go great for...one of you!" And she hung up.
"Well, that was weird" thought Mark.
------------------------------------------
Mark was watching football with some of his old college buddies over the weekend. He didn't really know these guys super well other than James, who he and Tiffany both knew from the football team. James wasn't much of a success after college, but for some reason he'd hung out with Tiffany (she swore they'd never hooked up) and Mark had watched the team on the weekends. He was a big guy, about 6'2", with a muscular build and a group of equally attractive friends. Jessica's suggestion popped into Mark's head. "Am I really going to do this?" he thought? Fuck it.
"James, I've got a question for you" he said out of earshot of the others.
"Shoot, man. What do you need?"
"Well, you know Tiffany obviously. I'm kind of worried she might want to cheat on me, and I was hoping you could, I dunno, hit on her for me? I want to see what happens."